docs: def _get_minmax_edges(self, edge):
          '''
          Updates the upper and lower depths based on the input edges
          '''
          if isinstance(edge, Line):
              # For instance of line class need to loop over values
              depth_vals = np.array([node.depth for node in edge.points])
          else:
              depth_vals = edge[:, 2]
  
          temp_upper_depth = np.min(depth_vals)
          if not self.upper_depth:
              self.upper_depth = temp_upper_depth
          else:
              if temp_upper_depth < self.upper_depth:
                  self.upper_depth = temp_upper_depth
  
          temp_lower_depth = np.max(depth_vals)
          if not self.lower_depth:
              self.lower_depth = temp_lower_depth
          else:
              if temp_lower_depth > self.lower_depth:
                  self.lower_depth = temp_lower_depth